A frequency-selective system that may be used as, or as part of, an add/drop multiplexer. An input signal is fed to a Mach-Zehnder interferometer configured to drop, or suppress, by destructive interference, a signal component in a first frequency band from among a plurality of frequency bands. One or more bandpass filters in one arm of the Mach-Zehnder interferometer suppress other frequencies, outside of the first frequency band, so that signals at these other frequencies are not suppressed by destructive interference and are present at the output of the Mach-Zehnder interferometer. A coupler connected after the output of the Mach-Zehnder interferometer adds, into the signal path, a replacement for the dropped signal.

A communication system in which a constellation employing partially anti-symmetric amplitude labels is used to transmit probabilistically shaped amplitudes such that said amplitudes are also used to determine the signs applied thereto for transmission. In an example embodiment, a data transmitter is configured to use a suitable logic function (e.g., an XOR function) to place the parity generated by an FEC code into a selected amplitude bit while using the partially anti-symmetric amplitude labels to avoid placing the parity into the sign bits of the transmitted constellation symbols. In some embodiments, the FEC code can be a low-density parity-check code. Some embodiments are compatible with layered FEC coding, e.g., employing an outer FEC code and an inner FEC code. In some embodiments, FEC coding may be optional. Some embodiments can advantageously be used in communication systems relying on DMT modulation, such as the systems providing DSL access over copper wiring.

According to one embodiment, a transmitter includes a 1st circuit configured to execute a 1st band limitation by waveform shaping in a time region with respect to 1st data relating to a 1st channel to generate a 1st signal; a 2nd circuit configured to execute a 2nd band limitation by the waveform shaping in the time region with respect to 2nd data relating to a 2nd channel to generate a 2nd signal; a 3rd circuit configured to generate a 3rd signal based on the 1st signal and a 1st frequency relating to the 1st channel; a 4th circuit configured to generate a 4th signal based on the 2nd signal and a 2nd frequency relating to the 2nd channel; and a 5th circuit configured to generate a 5th signal by multiplexing the 3rd signal and the 4th signal.

A multiplexer includes a common terminal connected to an inductance element at a connection path with an antenna element, filter elements including different pass bands and connected to the antenna element with the common terminal therebetween, and an inductance element arranged in series between a transmission filter with a largest capacitance when viewed from the antenna side among the filter elements and the common terminal. An inductive component of the inductance element and a capacitive component of the transmission filter element define an LC series resonant circuit, and a resonant frequency of the LC series resonant circuit is lower than any of pass bands of the filter elements.

Radio-frequency multiplexing systems, devices and methods. In some embodiments, a front-end system can include a quadplexer configured to support uplink carrier aggregation with a first antenna. The quadplexer can include a low-band filter, a mid-band filter, a first high-band filter, and a second high-band filter, with each filter having a respective input node, and the quadplexer including a common output node associated with the first antenna. The front-end system can further include a triplexer configured to support uplink carrier aggregation with a second antenna. The triplexer can include a mid-band filter, a first high-band filter, and a second high-band filter, with each filter having a respective input node, and the triplexer including a common output node associated with the second antenna.

A multiplexer (1) used in a communication device (5) includes an antenna (21) for a first frequency band group including 5GNR and an antenna (22) for a second frequency band group and includes a filter (12) for a first communication band and a filter (13) for a second communication band. The second frequency band group is higher than the first communication band, the second communication band is lower than the first communication band, the filter (12) includes a resonant circuit (31), an inductor (L1) connected to a node (n1) in a series arm path, and an inductor (L2) magnetically coupled with the inductor (L1).

A computing device (such as a computer gaming console) uses only a single radio to concurrently communicate with a wireless network access point and wireless client devices such as game controllers or peripherals. To establish and maintain both a high-throughput link with the access point, and a low-latency link with the client device(s), the single Wi-Fi radio of the computing device is configured to periodically switch between a channel used for the high-throughput link and a different channel that is used for the low-latency linkthus implementing a combination of frequency division multiplexing (FDM) and time division multiplexing (TDM). The console may use aspects of the Wi-Fi protocol standard to ensure that periodically switching its single radio between the two channels is accomplished while maintaining reliable communication on both channels.

A multiplexer includes: a low-pass filter that is connected between a common terminal and a first terminal and is formed of one or more first inductors and one or more first capacitors; a bandpass filter that is connected between the common terminal and a second terminal, has a passband higher than a passband of the low-pass filter, and is formed of one or more second inductors and one or more second capacitors; a high-pass filter that is connected between the common terminal and a third terminal, has a passband higher than the passband of the bandpass filter, and is formed of one or more third inductors and one or more third capacitors; and a fourth inductor that has a first end coupled to the common terminal and a second end coupled to the high-pass filter.

A linear, low noise, high quality factor (Q) and widely tunable notch filter circuit includes one or more first reactive elements coupled between a first filter node and a first node. The notch filter circuit further includes a multi-branch circuit having multiple parallel branches and coupled between the first node and a second node. Each branch of the multi-branch circuit includes at least a switch coupled to a variable capacitor. A notch frequency of the notch filter circuit is tunable by adjusting a capacitance of the variable capacitor.

A frequency-selective system that may be used as, or as part of, an add/drop multiplexer. An input signal is fed to a Mach-Zehnder interferometer configured to drop, or suppress, by destructive interference, a signal component in a first frequency band from among a plurality of frequency bands. One or more bandpass filters in one arm of the Mach-Zehnder interferometer suppress other frequencies, outside of the first frequency band, so that signals at these other frequencies are not suppressed by destructive interference and are present at the output of the Mach-Zehnder interferometer. A coupler connected after the output of the Mach-Zehnder interferometer adds, into the signal path, a replacement for the dropped signal.